Security Bypass Affecting microsoft.aspnetcore.app package, versions [,2.1.22) [3.0.0,3.1.8)


0.0
high

Snyk CVSS

    Exploit Maturity Proof of concept
    Attack Complexity Low
    Integrity High
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NVD
7.5 high
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RHEL
7.5 high

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  • Snyk ID SNYK-DOTNET-MICROSOFTASPNETCOREAPP-610167
  • published 9 Sep 2020
  • disclosed 8 Sep 2020
  • credit Matt Langlois of Github Security Team

How to fix?

Upgrade Microsoft.AspNetCore.App to version 2.1.22, 3.1.8 or higher.

Overview

Microsoft.AspNetCore.App is a package that provides a default set of APIs for building an ASP.NET Core application.

Affected versions of this package are vulnerable to Security Bypass. The ASP.NET Core cookie parser decodes entire cookie strings which could allow a malicious attacker to set a second cookie with the name being percent encoded. The security update addresses the vulnerability by fixing the way the ASP.NET Core cookie parser handles encoded names. This CVE also affects Microsoft.Owin due to it using a similar cookie parsing mechanism.